Powertrain, generic (extended)

P2805 Transmission Range Sensor A/B Correlation

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

Both range sensor signals are valid on their own, yet they do not agree. Many designs output two complementary pulse-width signals whose duty cycles must add up to 100 %. GM reads signal A in the transmission module and signal B in the engine module and sets P2805 as Type A when the sum is off by more than 4.849 % (2020 table) or 5.2 % (2025) for 1 s of 1.5 s. Ford allows plus or minus 4 % on its six- and ten-speed automatics (2024) and used the same principle on the DPS6 (2012). Audi bulletin 2051686 for 2016-2017 A6 links P280500 with a no-start and a gearbox message, cured by a new drive position sensor G676 plus TCM. Single-signal faults are P0705-P0709 and P2800-P2804.

Likely causes

Range sensor with one drifting output
Added resistance or poor ground in one of the two signal paths
Fault in the reading control module

Symptoms

  • MIL and gearbox warning on
  • Engine will not start or selector position not accepted
  • Substitute gear or limp operation

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–1,500
Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

transmission range sensor atransmission range sensor btcm

Related codes

P0705P2800P0706P2801P26C3

References: gsi.ext.gm.com, gsi.ext.gm.com, fordservicecontent.com, static.nhtsa.gov.